In a wide-area working site such as quarries and mines, vehicles for performing the carrying task of earth and sand are used. In performing the earth and sand carrying task, in order to avoid accidents due to fatigue of vehicle drivers (workers), to achieve manpower saving and to improve productivity by elongating working hours, there have been introduced unmanned vehicular driving systems for putting unmanned dump trucks in operation in place of manned vehicles such as manned off-road dump trucks.
In a working site where unmanned dump trucks are driven, there are areas such as a loading site, an earth unloading site and a fuelling station. These areas are connected by a well-maintained conveying road called a haul road, a lead-in road leading from the haul road to each of the areas called an access road and crossover points.
The loading site, which is one of the areas, is a place where an operation of loading earth and sand onto unmanned dump trucks (called “unmanned vehicles” in the present invention) is performed, and an excavation operation is performed by manned working vehicles (called “loaders” in the present invention) such as wheel loaders (front-end loaders), backhoes and shovels (for example, hydraulic shovels) and an operation of loading earth and sand onto unmanned vehicles.
FIG. 1A illustrates a loading site 1.
Referring to FIG. 1A, a driving path 10 is generated along which an unmanned vehicle 20 is caused to travel from an entry point 11 of the loading site 1 to a loading point 12 where a loader 30 exists, and the unmanned vehicle 20 is controlled to travel along the generated driving path 10. The loading point 12 is a position where earth and sand scooped by a bucket of a working machine 30a provided in the loader 30 are loaded in a load-carrying platform (also called a vessel) of the unmanned vehicle 20.
In this case, the unmanned vehicle 20 travels from the entry point 11 to arrive at the loading point 12 by way of a switch-back point 13 as a stopover point 14 located near the loading point 12. The switch-back point 13 is a point where switching between forward and reverse travels is performed at the time of switch-back operation that, after the unmanned vehicle 20 travels forward, it switches to a reverse travel to approach the loading point 12. But, the switch-back is not always required depending on loading patterns. For example, the vehicle 20 sometimes travels from the entry point 11 toward the loader 30 while describing an arc and exits the loading site 1.
Referring now to FIG. 1B, as the loader 30 such as a hydraulic shovel moves to a new excavation site or the like as the operator of the loader 30 operates to travel a traveling body (lower traveling body comprised of caterpillar belts or tires) of the loader 30, the position of the loading point 12 is moved sequentially. Incidentally, the above phrase “a movement or the like” is used because a swivel of the working machine (such as the bucket) 30a sometimes moves the loading point 12 without any movement of the loader 30 itself. For example, the position of the loading point 12 sometimes moves without any movement of the loader 30, as the operator of the loader 30 operates to drive the upper rotating body of the loader 30a causing a change in the approach angle of the unmanned vehicle 20 relative to the loader 30, due to the swivel of the working machine. That is to say, the position of the loading point 12 moves when the loader 30 performs the following three actions.
1) Movement+swivel
2) Movement only
3) Swivel only
When the position of the loading point 12 moves, it is necessary to set a new switch-back point 13′ generate a new driving path 10′ (shown in dashed line in FIG. 1B) to and make the unmanned vehicle 20 travel along the driving path 10′ to guide the unmanned vehicle 20 to a new loading point 12′. That is to say, the unmanned vehicle 20 needs to travel from the entry point 11 to the new loading point 12′ in the loading site 1 by a distance as short as possible to thereby improve production efficiency, realize low fuel consumption and suppress the cost.
(Conventional Working Technology)
According to a conventional unmanned vehicle driving system, when the position of the loading point 12, the direction of the unmanned vehicle 20 at the loading point 12, the entry point 11 of the loading site 1, and information on a boundary line 1A of the area of the loading site 1 are given, a supervising device 40 described later and shown in FIG. 5 searches automatically for a position of the switch-back point 13 and generates automatically the driving path 10 leading from the entry point 11 to the loading point 12 via the switch-back point 13.
(Prior Art 1 in Patent Documents)
The patent document 1 discloses an invention in which a circular course where an unmanned dump truck travels circularly is formed in a loading site and, when the position of a loading point moves, an approaching course, which is in contact with a vehicle stop position (switch-back point) on the circular course at a predetermined swivel radius and leads to the moved loading point, is automatically generated by computing, the unmanned dump truck traveling along the circular course is stopped at the vehicle stop position (switch-back point) and caused to perform a reverse travel to the loading point along the approaching course of the circular course (especially paragraphs 0012 through 0014 and FIG. 1 and FIG. 4 of the patent document 1).
(Prior Art 2 in Patent Documents)
The patent document 2 discloses an invention in which a predetermined drive pattern in a loading site is previously set and, when the position of a loading point moves, the position of a new loading point is determined by measuring or computing, and a driving path leading to the new loading point via a switch-back point is generated according to a previously set drive pattern (especially paragraph 0052 and FIG. 7 of patent document 2).    Patent document 1: Japanese Patent Application Laid-Open No. H05-257529 (especially paragraphs 0012 through 0014 and FIG. 1 and FIG. 4)    Patent document 2: Japanese Patent Application Laid-Open No. H08-263138 (especially paragraph 0052 and FIG. 7)